Growing demand in today's market for bandwidth, increased data rates, and satellite communications mobility has led to increasing use of high frequency radio frequency bands for satellite communications. This has resulted in a corresponding need for communication system components that function at these high frequencies. In many cases, these communication systems operate in the microwave frequency range, between 300 MHz and 300 GHz.
Among the components typically required in such systems are high powered amplifiers (HPA). Some existing high frequency high power amplifiers (HPA) employ traveling wave tube amplifiers (TWTA's). These devices require high voltage power supplies. They are also susceptible to single point failure and to achieve linear operation, these devices typically operate within a narrow operational range. In addition, TWTA's tend to be large and heavy, and demonstrate poor reliability, which is not optimal for many technologies, including satellite technology.
Some HPAs are solid-state devices. In contrast to TWTA's, solid-state amplifiers are small, efficient, relatively inexpensive, and reliable. However, a limitation of solid-state amplifiers is their low power output, which is too low for satellite transmission. This limitation has often been overcome through power combining, by combining the outputs of multiple relatively low power amplifiers.
The combining and splitting stages known in the prior art have included spatial combiners and corporate combiners. In spatial combiners, power is split and combined using fields in space, according to well-known antenna technology. In corporate combiners, the splitting and combining occurs as the signals follow branching transmission line paths.
The transmission line paths used in corporate combiners of the prior art have included microstrips and waveguides. A disadvantage of using microstrips is the high losses associated with splitting and combining of a high power signal, and the limited bandwidth in which they may be used. A disadvantage of the corporate combiners of the prior art which have employed waveguides has been that the splitting and combining have occurred in “magic tee” junctions, which are bulky and expensive to manufacture.
There remains, therefore, a need for a high power amplifier that can perform at super high frequencies, that is reliable, efficient, relatively light, and inexpensive to manufacture.